One purpose of a VPN is to interconnect multiple remote offices, nodes or sites with one another and/or a central office or node and thereby offer unified services such as, among many other possible applications, database access, email, calendaring, inventory control, etc. Thus, for example, a national retail chain might want to implement a VPN to interconnect individual stores with a central office and with one another. In such a scenario, the underlying network may comprise a vast number of individual computers and local area networks (LANs) or combinations thereof. A given VPN that leverages these networked computers and LANs may thus have multiple branches, leveraging multiple physical routing devices and interconnections to handle the geographically distributed nature of the physical stores and central office.
To better serve the growing VPN marketplace, service providers are increasingly relying on MPLS VPNs for geographically separated customer sites. An MPLS VPN comprises a customer network and a service provider network. MPLS VPN service provider edge (PE) routers store customer routing information enabling the PE routers to route traffic belonging to respective customers for inter-site traffic. That traffic is delivered to the customer sites via respective customer edge (CE) routers.
In an MPLS VPN implementation, a PE router performs multiple functions. For example, the PE router isolates customer traffic if more than one customer is connected to the PE router. Each customer is, accordingly, assigned an independent routing table. The PE router shares theses routing tables with other deployed PE routers so that customer traffic can seamlessly flow between customer sites via the service provider's own network or backbone. The protocol for sharing this routing information between PE routers is the multiprotocol border gateway protocol (MP-BGP). Considering the complexity of such MPLS VPN implementations, a continuing challenge for service providers is to efficiently manage their networks on behalf of their customers.